fix(chatgpt): omit temperature from subscription requests (#6498)

Co-authored-by: Raul <9117159+raultcj@users.noreply.github.com>

tests/test_llm_core_temperature_reasoning.py

@@ -156,3 +156,18 @@ def test_chatgpt_subscription_payload_omits_max_output_tokens_when_zero():
     )
 
     assert "max_output_tokens" not in payload
+
+
+@pytest.mark.parametrize("model", ["gpt-5.6-luna", "gpt-6-luna", "gpt-6-sol", "gpt-6.1-sol", "gpt-4.1"])
+def test_chatgpt_subscription_payload_omits_temperature_for_every_model(model):
+    payload = llm_core._build_chatgpt_responses_payload(
+        model,
+        [{"role": "user", "content": "Say OK"}],
+        temperature=0.2,
+        max_tokens=37,
+        stream=True,
+    )
+
+    assert "temperature" not in payload
+    assert payload["stream"] is True
+    assert payload["store"] is False